My rental car this weekend seems to have a feature where the radio gets louder when you go faster (and the engine/ car noise goes up). It works pretty well, but not perfectly.
But, really, how hard would it be to put a beat detector on the radio and sync the turn signals up with it? I’m pretty sure the turn signals are already run off of a microprocessor (through probably a FET) in modern cars, so it’d just be another sensor and a bit more code.
 I can’t find anything about the Chevy Cobalt doing this online but I’m pretty sure it does?